Migraine is the most common headache causing patients to consult a physician. According to the American Migraine Study II, approximately 28 million people in the United States aged 12 and older (approximately 13 percent of the population) suffer from headaches that fit the medical definition of migraine established by the International Headache Society. This corresponds to one migraine sufferer in every four U.S. households. The percentage of patients whose headaches fit the medical definition of migraine who are being diagnosed has increased compared to a decade ago. A majority of all migraine sufferers (53 percent) characterize their pain as causing either severe impairment or forcing them to retreat to their beds sometimes for days at a time. There have been no dramatic changes in the way physicians approach the treatment of migraine in the past 10 years. (Lipton R B et al., Headache, (2001) 41:638-645, 646-657)
A three-item Identification of Migraine (ID Migraine) clinical decision rule for the diagnosis of migraine has been developed. (Stewart W F et al., Neurology 1994;44(6 suppl 4):S17-23.) A migraine is a type of primary headache that some people get repeatedly over time. Migraines are different from other headaches because they occur with symptoms such as nausea, vomiting, or sensitivity to light. In most people, a throbbing pain is felt only on one side of the head. Migraines are classified as either “with aura” or “without aura.” An aura is a group of neurological symptoms, usually vision disturbances that serve as warning sign. Patients who get auras typically see a flash of brightly colored or blinking lights shortly before the headache pain begins. However, most people with migraines do not have such warning signs.
Multiple humoral agents have been postulated as being the major factor in migraine. These include serotonin, histamine, prostaglandins, platelet factors, endorphins, and vasoactive neuropeptides. The etiology of migraine has been studied by many investigators. Present research no longer fully supports the vasodilator/vasoconstrictor mechanism of vascular headache, i.e., arterial dilation causes pain and constriction equals relief. Research also has now implicated a sterile inflammation, possibly occurring in the dura mater, as the causative factor for vascular head pain. An unknown trigger activates perivascular trigeminal axons, which release vasoactive neuropeptides (substance P, calcitonin gene-related peptide, etc.). These agents produce the local inflammation i.e., vasodilation, plasma extravasation, mast cell degranulation which cause transmission of impulses to the brain stem and higher centers which in turn register as head pain (Moskowitz, M. A. (1992) Neurogenic versus vascular mechanisms of sumatriptan and ergot alkaloids in migraine. Trends Pharmacol. Sci. 13, 307-311).
Migraine therapy is either prophylactic or symptomatic. Prophylactic medication may be selected for a patient having two to four or more headaches per month, if they are severe enough to interfere with daily activities. Beta blockers such as propranolol (INDERAL®) are the most commonly used. Other medications frequently used include serotonin antagonists such as methysergide maleate (SANSERT®), calcium channel blockers (VERAPAMIL®), amytryptyline (ELAVIL®), and ergotamine preparations with belladona alkaloids and phenobarbital. All of these medications have significant side effects including sedation, loss of energy and drive, dry mouth, constipation, weight gain, and gastrointestinal cramping and distress. For symptomatic treatment, ergotamine with caffeine (CAFERGOT®) is commonly used. Other medications employed for treating migraine include isometheptene mutate (MIDRIN®), non-steroidal anti-inflammatory drugs (NSAID's such as MOTRIN®, NAPROXEN®, etc.), dihydroergotamine and the newer triptans, such as sumatriptan (IMITREX®), etc. When narcotics, such as FIORINAL WITH CODEINE® (butalbital with codeine) are used frequently, additional hazards, including the considerable potential for rebound headaches and habituation are encountered.
The administration of serotonin agonists is well established for the treatment of migraine headache. The serotonin agonists most widely used are the triptans, including sumatriptan, zolmitriptan, naratriptan, rizatriptan, eletriptan, frovatriptan and almotriptan. These compounds bind specifically to serotonin 5-HT1D/1B receptors. To a lesser degree, ergot alkaloids such as ergotamine tartrate (referred to herein as ergotamine) and dihydroergotamine mesylate (also referred to as dihydroergotamine or DHE) are also used to a variety of disease states, including, but not limited to the treatment of acute migraine.
Ergotamine and DHE have very low rectal, oral, sublingual and intranasal bioavailability (only 2% to 10% of the administered dose reaches the systemic circulation). These administration routes also result in relatively slow onset of therapeutic efficacy, ranging from 45 minutes for intranasal to 2 hours for oral or sublingual delivery. IV administration has high bioavailability and onset of therapeutic efficacy, usually much less than 30 minutes. However, injections are painful, cause local inflammation, reduce compliance, and because administration by IV requires costly clinical supervision, it would be very desirable to administer the ergot alkaloids by pulmonary inhalation. Pulmonary inhalation of the ergot alkaloids would minimize metabolism before the drugs can reach the circulation because there is rapid transport from the alveolar epithelium into the capillary circulation and because of the relative absence of mechanisms for metabolism in the lungs. Pulmonary delivery has been demonstrated to result in up to 92% bioavailability in the case of ergotamine tartrate. Pulmonary inhalation administration would also avoid gastrointestinal intolerance typical of migraine medications and minimize the undesirable taste experienced with nasal and sublingual administration due to the bitterness of the ergot alkaloids. Pulmonary inhalation would minimize the reluctance to administer treatment associated with the invasiveness of injection and the cost of clinical supervision. Pulmonary inhalation also would allow for rapid relief from the migraine symptoms, as it would deliver the drug to the systemic circulation as fast as an IV bolus, less than 30 minutes, without the invasive nature of injection.
Dihydroergotamine (DHE) was identified as an effective treatment for migraine nearly fifty years ago (Raskin, Neurology 36:995 997 (1986); Silberstein, et al., Headache 30:334 339 (1990); Saadah, Headache 32:18 20 (1992); and Winner, Headache 33:471 475 (1993)). Despite numerous references describing aerosol delivery of ergotamine tartrate, also referred to as ergotamine, for pulmonary inhalation, there are few, if any, teachings related to the delivery of DHE via pulmonary inhalation. Delivery of DHE in the same manner as ergotamine tartrate is not easily accomplished because DHE is very difficult to stabilize in any of the above formulations. DHE (D.H.E. 45®—Novartis) has been administered by intramuscular or intravenous (IV) injection for over 50 years (Belgrade, et al., Neurology 39:590 592 (1989); Winner, Headache 33:471 475 (1993)). DHE (MIGRANAL®—Novartis) has been administered by nasal administration for 10 years. DHE is also effective when given subcutaneously (Klapper, et al., Headache 32:21 23 (1992); Winner, et al., Arch. Neurol. 53:180 184 (1996); and Becker, et al., Headache 36:144 148 (1996)). However, its administration has been associated with an undesirable side effect profile: nausea, emesis, chest tightness and related cardiovascular effects such as blood pressure instability and arterial constriction, have been reported with its use.
Although effective in the treatment of migraine, DHE administration is often accompanied by side effects such as nausea, vomiting and chest pain (Winner, et al., Arch. Neurol. 53:180 184 (1996)). Other side effects observed from postmarketing experience in patients receiving D.H.E. 45® (dihydroergotamine mesylate) injection, USP, include vasospasm, paraesthesia, hypertension, dizziness, anxiety, dyspnea, headache, flushing, diarrhea, rash, increased sweating, cardiac valvulopathy, and pleural and retroperitoneal fibrosis seen after long-term use of dihydroergotamine. At least one side effect, nausea, occurs more frequently after intravenous administration than after intramuscular or intranasal administration. When given subcutaneously at a concentration of only 1.5 mM, DHE has been reported to cause nausea in nearly 16% of treated patients (Winner, et al., Arch. Neurol. 53: 80 184 (1996)). The currently accepted treatment algorithms for injection or IV use of DHE (see FIGS. 6A-6B) call for the administration of an antiemetic prior to or concurrent with administration of DHE to prevent nausea. Patients with known cardiovascular disease are not qualified to receive DHE treatment.
Notwithstanding these undesirable side effects DHE is still considered the “gold standard” for treatment of severe migraine, cluster headache, chronic daily headache. DHE has a longer duration of action than sumatriptan, so headache recurrence rates are lower with its use. (Winner P, et al. A double blind study of subcutaneous dihydroergotamine versus subcutaneous sumatriptan in the treatment of acute migraine. Arch Neurol (1996) 53:180-184.) Thus, there exists a need for procedures to deliver therapeutically effective amounts of DHE in a time-sensitive manner, without precipitating the side-effects traditionally associated with its administration.